kriging
Ok, What about higher order polynomials? I have fitted one using a gam to the data which which helps to normalize the residuals, and reduce the variance of the residuals. Is it simply a matter of plugging in the function into the gstat command line? Or is it simpler to krig the residuals and then add the trend back to the interpolated residual grid?
Paulo Justiniano Ribeiro Jr wrote:
Dave, what is necessary for UK is a relation expressed by a linear model, not necessaraly a linear relation between the variables. e.g. you could have a second degree polinomial and still work within the scope of universal kriging. On Mon, 16 Jun 2008, Dave Depew wrote:
Hi all, I have a data set that I would like to krige to interpolate between transects. There is a non-linear trend between two of the variables...my impression from reading the gstat help file is that there must be a linear relationship between the data to use universal kriging? Second, would a method of non-linear regression followed by modelling of the residuals with a semivariogram be an appropriate solution? Thanks, Dave
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Paulo Justiniano Ribeiro Jr LEG (Laboratorio de Estatistica e Geoinformacao) Universidade Federal do Parana Caixa Postal 19.081 CEP 81.531-990 Curitiba, PR - Brasil Tel: (+55) 41 3361 3573 Fax: (+55) 41 3361 3141 e-mail: paulojus AT ufpr br http://www.leg.ufpr.br/~paulojus